Characterization of commensal Escherichia coli through genetic content and Flagellin structure

Abstract

Inflammatory bowel disease (IBD) is a steady health concern in the developed world and an increasing problem in emergent economies. IBD manifests as inflammation in the intestinal tract, impacting significantly the quality of life of the patients coping with the disease and in turn representing a major burden to the healthcare system. Current IBD diagnosis is invasive and the treatment carries considerable side effects. The precise IBD etiology is unknown. Nevertheless, factors such as genetic conditions of the individual, environmental elements and the gut microbiota composition (GM) are among the most relevant elements associated with IBD. Functional alteration of the GM composition is termed dysbiosis. In this state, an increase in proteobacteria such as E. coli and a general reduction in diversity are strongly associated with IBD. One of the research fronts in this work aimed at the genetic characterization of E. coli associated with a dysbiotic state. In a second project we analysed the probiotic effects of the surface protein flagellin (FliC) from the symbiotic bacterium E. coli Nissle 1917 (EcN), which has been used to treat IBD. Through the analysis of the whole gene content from a cohort of 50 E. coli coming from healthy and IBD carriers, together with a simple prediction statistical tool, it was found that four genetic markers (IS3 family transposase, trbC, eheA and licT) correctly classified 83% of the E. coli isolates as IBD-specific. On the second project it was found that FliC from EcN (EcN FliC) is able to confer protection to mice against dextrane sodium sulfate (DSS)-induced acute colitis.

Die Dissertation ist gesperrt bis zum 05. Juli 2025 !